AIBU to question school swimming changing room supervision and safeguarding?

[NotMyPiggy]

My child is in Y3. They go swimming every week and ask for parent volunteers to accompany them to walk there. I have recently found out that on days when they struggle for a volunteer or staff, there has just been one Mum on her own accompanying the whole changing room of girls getting changed. This Mum hasn't been DBS checked (I suspect, because none of us are asked to be when we take a turn).
I am asking whether this is usual from a safeguarding perspective?

Are you sure she is actually inside the changing room with the children. When I take my class swimming us adults stand at the door outside the changing rooms (it’s like a large private room within the public changing room, one for the boys and one for the girls, only one entrance / exit) and tend to yell in ‘hurry up, stop mucking’ yada yada yada, from the door.

Are the kids in cubicles, or one big room?

Is it a big communal changing room and she goes inside it , instead of waiting outside? Or are there individual/group cubicles and she is waiting outside? The actual set up matters. As school staff we avoid being present when children are changing, unless something happens or it is required by the individual needs of a child. It would be very odd for an adult(DBS checked or not) to be required to actively supervise changing children .